John Robie (Cary Grant) is a notorious but retired jewel thief or “cat burglar,” nicknamed “The Cat,” who now tends to his vineyards in the French Riviera. A series of robberies that closely resemble his in style leads the police to believe that the Cat is up to his old tricks again. They come to arrest him, and he adeptly gives them the slip.

He immediately seeks refuge with his old gang from his days in the French Resistance, a group of ex-cons whose patriotic work led to grants of parole that depend on them keeping their noses clean. Bertani, Foussard, and the others are all under a cloud while the Cat is at large, and they blame Robie. Still, when the police arrive at Bertaniâ€™s restaurant, Foussardâ€™s daughter Danielle (Brigitte Auber) spirits her old flame to safety.

Robie enlists the aid of an insurance man of Bertani’s acquaintance, H. H. Hughson (John Williams), in order to prove his innocence. Robie’s plan is to catch the new cat burglar in the act. To do this, he obtains a list of the most expensive jewels on the Riviera from the reluctant Hughson. The first names on the list are Jessie Stevens (Jessie Royce Landis) and her daughter Francie (Grace Kelly). Robie strikes up acquaintance with them â€” something met with delight by Jessie, a pretense of modesty with Francie, and claws-baring jealousy from Danielle.

…

Robie speeds back to his vineyard and Francie races after to convince him that he does need her in his life. He agrees, but seems less than thrilled about including her mother.

Photographer L. B. “Jeff” Jeffries (James Stewart) is recuperating from a broken leg and confined to a wheelchair in his small Greenwich Village apartment. He passes the time by spying on his neighbors through his apartment’s rear window, including a dancer who exercises in her underwear, a lonely woman who lives by herself, a songwriter working at his piano (Ross Bagdasarian), and several married couples, including a salesman, Lars Thorwald, (Raymond Burr) with a bedridden wife.

Every day Jeff is visited by Stella (Thelma Ritter), a cranky but friendly home care nurse and Lisa Fremont (Grace Kelly), his much-younger socialite girlfriend. Lisa is madly in love with Jeff, who returns her feelings but also believes that their lifestyles are incompatible. He talks to both Lisa and Stella about his neighbors. After the salesman makes repeated late-night trips carrying a large case, Jeff notices that the bedridden wife is now gone, and sees the salesman cleaning a large knife and handsaw. Later, the salesman ties a large packing crate with heavy rope, and has moving men haul it away. By now, Jeff, Stella, and Lisa have concluded the missing wife has been murdered by the salesman.

An old Army Air Corps buddy of Jeff named Tom Doyle (Wendell Corey) is now a police detective. He looks into the situation and finds that Mrs. Thorwald is in the country, has sent a postcard to her husband, and the packing crate they had seen was full of her clothes. Chastised, they all admit to feeling a bit ghoulish at being disappointed to find out there was not a murder. Jeff and Lisa settle down for an evening alone, but a scream soon pierces the courtyard when a dog belonging to a neighbor couple is found dead with its neck broken. The neighbors all rush to their windows to see what has happened, except for Thorwald, who sits unmoving in his dark apartment, the tip of his cigarette glowing.

…

A few days later the heat has lifted, and Jeff rests peacefully in his wheelchair; now with two broken legs from the fall. Lisa reclines happily beside him, appearing to read a book on Himalayan travel but turning, after Jeff is asleep, to a new issue of Harpers Bazaar, a fashion magazine.